The interaction of the SNAPs with SNAREs takes place before interaction of the complex with NSF (Sec18 in yeast) suggesting a sequence for the priming assembly may be necessary. SNAPs associate with the proteins of the SNARE ( SNAP REceptor) complex, a class of type II integral membrane protein, as well as the ATPase NSF, largely based on electrostatic interactions. According to the SNARE hypothesis developed in the early 1990s, SNAP protein are localized to the membranes and are central in mediating Ca 2+ dependent vesicle fusion at these sites. The function of SNAP proteins have been primarily related to the role which the play in the assemble and disassembly of SNARE complex required for vesicle fusion events. 1.1 Limitations of the Original SNARE Theory of Vesicle Fusion.The yeast homolog of the human SNAP is Sec17, the structural diagram of which is included on this page. α- and γ-SNAP are expressed throughout the body, while β-SNAP is specific to the brain. Mammals have three SNAP genes: α-SNAP, β-SNAP, and γ-SNAP.
The energy provided by NSF is transferred throughout the SNARE complex and SNAP, allowing the proteins to untangle, and recycled for future fusion events. Following membrane fusion, the tethering SNARE proteins complex disassembles in response to steric changes originating from the ATPase NSF. SNAPs are involved in the priming of the vesicle fusion complex during assembly, as well as in the disassembly following a vesicle fusion event. SNAPs interact with proteins of the SNARE complex and NSF to play a key role in recycling the components of the fusion complex.
Soluble N-ethylmaleimide-Sensitive Factor Attachment Proteins ( SNAP, or Sec17p in yeast) are a family of cytosolic adaptor proteins involved in vesicular fusion at membranes during intracellular transport and exocytosis. Sec17, a yeast homolog of the human SNAP, patriciates in membrane fusion of vesicles complexes with SNARE and NSF to mediate assembly and disassembly.
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